Experiment on Calcified Carbothermal Reduction Roasting of Zinc Containing Electric Furnace Dust

This is an article in the field of metallurgical engineering. In order to strengthen the effective separation and recovery of zinc and iron resources in zinc containing electric arc furnace dust(EAFD), and reduce the consumption of carbon reducing agent, the idea and method of calcified carbothermal reduction roasting with high basicity burden prepared from EAFD was proposed. Thermodynamic calculation and test study were combined, the main phase transformation during the calcified carbothermal reduction roasting process of EAFD was analyzed to explore calcified carbothermal reduction reaction behavior and path. It is shown that the reduction of ZnFe₂O₄ to Fe_0.85-xZn_xO inhibits the reduction and volatilization of zinc when the molar ratio of carbon to oxygen is less than 0.6 and the temperature is lower than 1000 ℃. While the calcification of ZnFe₂O₄ and Fe_0.85-xZn_xO to Ca₂Fe₂O₅ by adding CaO can promote the reduction of zinc and Ca₂Fe₂O₅ will be further reduced. When the temperature is lower than 1100 ℃ and n_c/n_o< 1.0, the reaction path of calcified carbothermal reduction roasting is ZnFe₂O₄ + CaO → Ca₂Fe₂O₅ + ZnO → Ca₂Fe₂O₅ + Zn (g) and Fe_0.85-xZn_xO + CaO → Ca₂Fe₂O₅ + ZnO + FeO → Ca₂Fe₂O₅ + Fe + Zn (g). Both of these reactions can promote the release of zinc. The results show that CaO can promote zinc volatilization in the range of n_c/n_o 0.4～1.2 and calcination temperature 1000～1100 ℃. The dezincification rate of calcified carbon thermal reduction roasting at n_c/n_o = 1.0 is close to that at n_c/n_o = 1.2, both of which are about 90%, so the consumption of carbon reducing agent can be reduced and energy consumption can be saved.